Nuclear Chemistry

Nuclear Chemistry
The branch of chemistry which studies the reactions involving the changes in the nucleus of the atom.
The change of one element into an entirely different element or elements resulting from a change in the number of protons.
Unstable Isotopes
Radioactivity (radioactive decay)
The spontaneous uncontrollable breakdown of an unstable atomic nucleus to produce other elements accompanied by the release of particles and rays.
Half Life
The length of time during which half of a given number of atoms of a radioactive substance decays.
A detection device worn by people who work with radiation, uses film exposure to measure the total amount of radiation a person has received.
Radioactive Series
A chain of transmutations, a chain reaction that will continue until a stable isotope is formed.
Geiger Counter
Used to detect radiation
When a radioactive isotope is substituted for a stable isotope of the same element. They are used to follow a specific substance as it moves through a natural system.
Radioactive Dating
The use of half-lives of radioisotopes in determining the age of the earth, ancient relics, and similar objects.
Somatic Injuries
Biological changes within the body tissue.
Genetic Injuries
Effect the reproductive cells and can result in hereditary changes.
The splitting of a heavy atomic nucleus into two fragments by being bombarded with neutrons.
Breeder Reactor
Fission reactor that not only produces energy, but manufactures another fuel.
Reactions between two or more light nuclei conbined to form one or more nuclei of less total mass.
How are Matter and Energy Related?
In nuclear reactions, matter can be converted into energy and energy into matter.
Who discovered radioactivity?
Henri Becquerel
How was radioactivity discovered?
Through his interest in the ability of
certain minerals to fluoresce (give off visible light after being exposed to sunlight.), he discovered that
uranium ore gave off invisible rays that penetrate the light proof covering of a photographic plate and
affect the film as if it had been exposed to light rays directly.
What effect did the discovery of radioactivity have on Dalton’s indivisible atom?
It killed the theory.
What caused the fogging of the photographic plates? Who made this discovery?
The rays emitted by the uranium in the ore ;pitch blend; caused the fogging. Discovered by Marie and Pierre Curie.
The Curies discovered which two elements?
Polonium and Radium
Compare the radioactivity of radium and uranium.
Radium is 2 million times more radioactive.
State the characteristics of the transuranium elements.
None occur in nature, radioactive, synthesized, atomic numbers greater than 92.
How are new elements synthesized?
In nuclear reactors and nuclear accelorators, which accelerate the bombarding particles to very high speeds.
How do radioisotopes gain stability?
By making changes within their nuclei.
As related to the periodic table, at what point are all the nuclei radioactive?
All nuclei with an atomic number greater than 83.
What determines the stability of the nucleus?
The ratio fo protons to neutrons.
1-20= 1:1
Larger= 1:1.5
Label the diagram:
a= mass number
x=particle or element
b=atomic number or charge
List the three types of radioactive emmision.
Alpha, Beta, Gamma
What is an alpha particle? What is it’s mass and charge?
It has a mass of 4 atm and positive 2 charge.
Discuss the penetration ability of alpha particles and how they can be stopped.
Low penetrating ability- can be stopped by a single sheet of paper or even dead cells on the surface of skin.
When are alpha particles dangerous? Explain.
They are dangerous when ingested- they can penetrate the soft tissue of the body and cause damage.
What is a beta particle? What is the mass and charge of a beta particle?
They are electrons. No mass, and a charge of -1.
Discuss the penetration ability of beta particles and how they can be stopped.
They are almost 100x more penetrating than alpha particles. They can be stopped by a thin sheet of aluminum or thin sheets of wood.
How is the beta particle formed?
When the nucleus is disrupted, the elements have too many neutrons to become more stable by the breaking apart of a neutron to form a proton and an electron. The electron is shot our as a beta particle.
1 1 0
n —> p + e
0 1 -1
How does the proton number of an atom change after the release of the beta particle?
The elements that have too many nuetrons become more stable by the breaking apart of a neutron to form a proton and an electron.
What are gamma rays?
High energy electromagnetic waves.
Except for their origin, ______ are essentially the same as gamma rays.
What is the mass and charge of gamma radiation?
It has no mass or charge
Discuss the penetration ability of gamma rays and how they can be stopped.
They have 1000 times the penetrating ability of alpha. They can be stopped by several meters of concrete or several cm of lead.
What causes gamma radiation to be released? When does this happen?
Gamma radiation is released, after alpha and beta emission, when the remaining nucleons (protons and neutrons) reorganize into a stable arrangement.
List the properties of the radioactive elements.
Affect the light sensitive emulsion on photographic film, produce an electrical change in the surrounding air, they produce flourescence with certain other components, undergo radioactive decay.
What is the purpose for adding radium bromine to zinc sulfide?
It causes the zinc sulfide to glow
State the harmful effects of radiation.
Can destroy the germinating power of seeds, can kill animals, may cause serious burns, can be fatal.
What isotope is important in radioactive dating?
Carbon- 14
What instrument is used to follow a tracer throughout a living system?
A geiger counter
The chemical properties of two isotopes, one stable and one radioactive, are the same. Explain why this is true. How is the radioactivity of an element affected by chemical combination? Explain.
Chemical properties of an element are determined by the number and arrangement of valence electrons. Isotopes have the same number and arrangement of valence electrons and therefore will have the same chemical properties even if one is radioactive.
Radioactivity is a nuclear property and is determined by the ratio of the protons to the neutrons. Chemical combination involves only the valence electrons and will not change the nucleus of the atom. The radioactivity of an atom is not affected by chemical combination.
List the beneficial uses of radioactivity. Give specific examples.
Radioactive dating, tracers (medical and industrial), cancer treatment, food preservation, sterilize surgical equipment.
What is the source for the fission reactors?
Which type of nuclear reaction is considered the best? Why?
Fusion- power plants would produce little waste, fuel is obtained from water, releases more energy than fission.
State the disadvantages of both types of nuclear reactions.
Fission- products are highly radioactive and cannot by discared as ordinary waste, and thermal pollution- the heating of water used as a coolant in some reactors when returned to the environment can kill the existing marine life.

Fusion- very high temperatures are required for a reaction- 40 million degrees K, and a containment vessel that won’t melt.

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